Though tempura is one of the most famous traditional Japanese food, you won't see as many specialized restaurants in Japan as sushi restaurants. This place has been one of the best for more than 100 years and definitely a must-visit-tempura restaurant.
reasons why you should visit
1)quality of food: absolutely great. Each ingredients are cooked in perfect timing and served one by one, so that you can enjoy and focus on the flavor.
2)location: right by the Shinjuku station (West gate). If you stay in Tokyo, it is super easy to get there.
3)service: as you expected at family-owned restaurant, you will experience very warm hospitality. They even have English menu for non-japanese speakers.
Hope you guys enjoy great tempura and Japanese culture here!